Forces revision

  • Friction & Drag

  • Compression

  • Turning Forces

  • Moment equation

  • Pressure in Solids

  • Pressure in Gases

  1. Friction and Drag

Contact forces Non contact forces

  • friction a) Electromagnetic force

  • gravity b) nuclear force

  • air resistance c) Magnetic force

  • upthrust

  • thrust

Independent variable- the variable that you change

Dependant variable- the variable you measure

  1. Compression

COMPRESSION is the result of forces squashing an object

TENSION is the result of forces stretching an object

  1. Turning forces

a MOMENT is a turning effect that a force produces on an object with a pivot or fixed point about which it can turn

2 factors in opening a door

a. distance from pivot

b. force applied

  1. Moment equation

MOMENT= FORCE (N) x DISTANCE from pivot (cm or m)

FORCE x DISTANCE = MOMENT

MOMENT Ă· DISTANCE = FORCE

MOMENTĂ· FORCE = DISTANCE

  1. Pressure in solids

  • Pressure is measured in Newtons per square metre (N/m²)

  • It is also measured in Newtons per square centimetre (N/cm²)

  • The smaller the surface area of a solid, the less force is required

  • The bigger the surface area of a solid, the more force is required

  • Increasing the force will increase the pressure in any situation

  • FORCE = PRESSURE (N) x AREA (m/cm)

  1. Pressure in Gases

  • The higher in the atmosphere we go the less air directly above us, and the temperature decreases

  • The pressure of liquids changes with depth the deeper you go:

    i) The greater the weight of liquid above

    ii)the greater the liquid pressure

  • Upthrust acts on any object that is floating or submerged in a liquid

  • There are more water molecules hitting the bottom of the object than air molecules hitting the top

  • If the area in contact with the liquid is too small there is not enough upthrust to balance the weight so it sinks